Cranial Features of the Spotted Seal, Phoca largha, in the Nemuro Strait, Considering Age Effects

Journal of Veterinary Medical Science

Noriyuki OHTAISHI¹  Ayako W MIZUNO¹ 

[1] Laboratory of Wildlife Biology, Graduate School of Veterinary Medicine, Hokkaido University

关键词: growth;    individual variation;    principal component analysis;    sexual dimorphism;    skull morphology;   

DOI  :  10.1292/jvms.64.137

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

References(23)Cited-By(9)Cranial features (development, individual variation, and sexual dimorphism) were examined from the 23 metrical characters and 2 nonmetrical characters (the degree of closure of the 9 cranial sutures and the presence of sagittal crest) in the two spotted seal specimen groups at the Nemuro Strait, Hokkaido. One specimen group was incidentally taken in the salmon trap nets between 1982 and 1983 (n=70), and the other was randomly sampled by damage control kill between 1997 and 1998 (n=82). The development of morphometrical characters of skulls ceased at 5.6, 10.7, 7.9, and 11.9 yr. old, for 1982-83 male, 1982-83 female, 1997-98 male and 1997-98 female, respectively. The sutures were half ankylosed till approximately 10 yr. old in both sexes. The sagittal crest began from about 5 yr. old in male. Individual variation of skull was large in the feeding, breathing, and facial-expression apparatus. On the other hand, the variation of braincase, and skull concerning to the movement of head/neck tended to be small. Only 1997-98 specimens exhibited a sexual dimorphism in skull characters except for the braincase, whereas the dimorphism was not found in 1982-83 specimens. We could not detect the significant difference between two specimen groups, although there were a few differences in characters related to the rostrum and mandible.

【 授权许可】

Unknown